The disclosure relates to electronic communications. More particularly, the disclosure relates to a dual conversion receiver for use in electronic communication systems.
In a typical frequency division multiplex communication system, multiple transmissions can simultaneously occupy a predefined operating band. The signals within the operating band can operate according to a predetermined communication standard, and thus, can have an energy within a predictable dynamic range. The communication standard can also specify a frequency spacing between adjacent channels, and the channel bandwidth. The communication standard can also specify signal parameters, such as modulation type, information rates, out of channel performance, as well as other signal parameters.
Additionally, there can be numerous signal sources operating outside of the operating band. Unlike the signals within the operating band, the out of band signals are typically not regulated by the communication standard regulating the in band signal performance. As a result, out of band signals may have substantially greater energy relative to the in-band signals, and can operate according to different signal parameters, including modulation type, out of band performance, and other parameters.
Examples of communication systems that use some form of frequency division multiplexing include, but are not limited to, television, radio, wireless communications, including cellular telephones, cordless telephones, and transceivers. Each of these communication systems can rely on the ability of a receiver to extract the desired signal from a host of interference sources.
Many receiver implementations have been developed to support the various communication standards. The trend of increasing device complexity and performance while simultaneously reducing the physical size of electronic devices imposes tremendous constraints on ongoing development.
For example, the size of cellular and cordless telephones continues to shrink while simultaneously improving the quality of the device and adding additional functionality to the device. Similarly, radios and televisions are constantly being redesigned to provide improved features while simultaneously decreasing physical size. Although the screen size available in television receivers continues to grow, the advancement of technologies that enable flat screens and short depths greatly reduce the volume available for electronics. The cavernous cabinet that was once associated with televisions is largely eliminated due to the advancement of screen technologies.
The complexity and corresponding performance of digital circuits, such as processors, has increased tremendously. The performance increase of digital circuits is accompanied by a corresponding decrease in the physical size required for a device performing the function of the digital circuits.
The size of analog circuits has decreased over time, and the performance of analog circuits has increased based on advancing architectures and materials. However, the advancement of analog circuits, particularly analog circuits for use in Radio Frequency (RF) applications, has not experienced the tremendous advancement seen in digital circuits.
In RF circuits, the quality of individual elements, such as inductors and capacitors, continues to exert a great influence on the performance of the associated RF circuits. As such, device miniaturization and communication system performance enhancement can be limited by the performance of the analog portions of a device, including the RF portions of the device.
Therefore, it is desirable to improve the performance of the analog portions of a device while simultaneously reducing the physical size occupied by the analog portions. In communication systems, it is desirable to increase the performance of the receiver while simultaneously reducing its physical size.